a
Chemistry Department, University of Pretoria, Private Bag X20, Hatfield, South Africa
E-mail: daniela.bezuidenhout@up.ac.za
;
Fax: +27-(0)12-420-4687
;
Tel: +27-(0)12-420-2626
b
Chemistry Department, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
E-mail: swartsjc@ufs.ac.za
;
Fax: +27-(0)51-444-6384
;
Tel: +27-(0)51-401-2781
c
Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense, 28040-Madrid, Spain